Detailed design work will begin later this year on a critical water supply tunnel that will run under Vancouver’s Stanley Park.
“The project is really important to supplying water to the Metro Vancouver area, and it is through a crown jewel park,” said Goran Oljaca, director of engineering and construction with Metro Vancouver water services.
A water main — known as Capilano Main No. 4 — already runs through the park. It is almost 90 years old and carries water from the Seymour-Capilano Filtration Plant to Vancouver, the Musqueam First Nation, Richmond, Delta and the Tsawwassen First Nation — about half of the water used in the City of Vancouver and one-third of the region’s drinking water.
The steel main, which is 1.8 metres in diameter, has experienced only minor leaks over the years, with the exception of a major breach near Lost Lagoon in August 2016, which took nearly a month to repair.
At that time, it was determined that the steel water pipe was reaching the end of its serviceable lifespan. Oljaca said Metro pipelines are typically designed and built to last anywhere between 80 and 100 years, but newer ones can last longer.
The new 1.4-kilometre tunnel will run from Burrard Inlet west of Lumbermen’s Arch to near Chilco and Alberni Streets, 40 to 60 metres underneath the park and Lost Lagoon. The new main, which will be 2.8 metres in diameter, is expected to have twice the capacity of the old one. The construction budget is around $125 million.
Oljaca said the new tunnel will be constructed using three shafts, with the main one where most of the work will take place potentially located north of the city’s service yard. Two exit shafts would be located at the north and south ends of the park.
“I think the important thing is Metro Vancouver, or Greater Vancouver Water District, is working closely with the City of Vancouver, the park board, and First Nations to make sure we do this important project and at the same time minimize impact of the construction,” Oljaca said.
Tiina Mack, the Vancouver park board’s manager of park development, said the collaboration has worked well so far. She said the board and Metro Vancouver staff are in contact regularly.
“It’s our role to take care of this park and make sure the project is done in a sustainable and safe manner for the park and its users,” Mack said.
Mack said it is important that the city, First Nations, Metro Vancouver and residents are working together to enhance the environment in Stanley Park as part of the project.
The project is currently in the preliminary design stage.
Late last year, Metro Vancouver conducted preliminary ground investigation work at six sites along the tunnel route. Oljaca said the geotechnical information shows that ground conditions are as expected.
That information will help Metro with the preliminary design, which is expected to be complete by October of this year. At that point, detailed project design will begin and last until late 2020. That is when Metro will issue a request for quotations and then a request for proposals. Construction should start in 2021 and continue until 2025.
Oljaca said the water main replacement is one of a number of major water projects that Metro Vancouver will undertake in the next decade or so, to address growth, system maintenance and system resiliency.
Projects include river crossings and looking at how the region can increase its water supply.
“We are looking 100 years into the future,” Oljaca said.
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